1. Field of the Invention
The present invention relates to surgical methods and associated apparatus therefor. More particularly, it relates to methods and means substantially directed to achieving improved kidney function in association with present day surgical transplantation technique.
2. Description of the Prior Art
Present day transplantation of the human kidney occurs in three qualitatively distinct stages. The first, sometimes referred to as "harvesting" involves the surgical removal of the kidney from the donor. It is during this stage that the kidney's blood supply is removed. Harvesting is followed by a storage-transport stage. During the storage-transport stage, the kidney must be maintained in a condition of hypothermia (below body temperature, 38.degree. C.) to decrease the oxygen needs of the organ. It has been found that significant deterioration of kidney function (warm ischemia) occurs when the kidney is maintained without blood supply at a temperature greater than 18.degree. C. Significantly, the cortex of the kidney, the location of the important urine filtration function, is located exteriorly and thus is particularly subject to warm ischemia when held in the surgeon's hand or against the donee's tissues.
Various methods have been employed, and meet with relative success for maintenance of the harvested kidney at adequate hypothermia for periods of up to forty-eight hours of time during the second or storage-transport stage. These include, but are not limited to, the (pumped) circulation of a cold solution (5.degree.-15.degree. C.) such as cryo-precipitated plasma and the storage of the kidney in a 0.degree. C. (ice) equilibrium bath of an intra or extra cellular electrolyte solution.
During the third stage, surgical re-implantation, the kidney is commonly held (positioned) by an assisting physician while the operating surgeon attaches the renal vein and artery and the ureter, a tube which carries the purified (filtered) urine to the bladder from the cortex of the kidney. This surgical procedure (or anastomosis) may be accomplished in about forty-five minutes, leaving the kidney with a new blood supply (the donee's) even as the suturing of the donee's surgical cavity incision proceeds.
It is during the period of time that the kidney is being surgically connected to the donee's blood supply that kidney deterioration due to warm ischemia takes place. This results from the fact that manual positioning of the harvested kidney, removed from the above-mentioned temperature preservative means of the storage-transport stage, is required by present surgical techniques. The kidney is at this time removed from all artificial storage-transport cooling systems and, having no functioning blood supply, subject to the effects of warm ischemia for the above-mentioned period of approximately forty-five minutes. The degree of deterioration of kidney function which takes place at this time is a direct function of the amount of rewarming that occurs. The success of the transplant will depend substantially upon the damage necessarily incurred by the transplanted kidney during anastomosis.